Ensure the multiple prop is typed correctly when passing explicit types to the Combobox component (#3099)

* ensure `TMultiple` is correct when passing explicit types to the `Combobox`

When you use the `Combobox` component with explicit types:

```ts
<Combobox<MyType> />
```

Then we make sure that we properly set the `TMultiple` prop as well. It
defaults to `false` which seems to be the better default.

* update changelog

packages/@headlessui-react/CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Keep focus inside of the `<ComboboxInput />` component ([#3073](https://github.com/tailwindlabs/headlessui/pull/3073))
 - Fix enter transitions for the `Transition` component ([#3074](https://github.com/tailwindlabs/headlessui/pull/3074))
 - Render hidden form input fields for `Checkbox`, `Switch` and `RadioGroup` components ([#3095](https://github.com/tailwindlabs/headlessui/pull/3095))
+- Ensure the `multiple` prop is typed correctly when passing explicit types to the `Combobox` component ([#3099](https://github.com/tailwindlabs/headlessui/pull/3099))
 
 ### Changed
 

packages/@headlessui-react/src/components/combobox/combobox.tsx

@@ -1830,11 +1830,12 @@ function OptionFn<
 // ---
 
 export interface _internal_ComponentCombobox extends HasDisplayName {
-  <TValue, TTag extends ElementType = typeof DEFAULT_COMBOBOX_TAG>(
-    props: ComboboxProps<TValue, true, TTag> & RefProp<typeof ComboboxFn>
-  ): JSX.Element
-  <TValue, TTag extends ElementType = typeof DEFAULT_COMBOBOX_TAG>(
-    props: ComboboxProps<TValue, false, TTag> & RefProp<typeof ComboboxFn>
+  <
+    TValue,
+    TMultiple extends boolean | undefined = false,
+    TTag extends ElementType = typeof DEFAULT_COMBOBOX_TAG,
+  >(
+    props: ComboboxProps<TValue, TMultiple, TTag> & RefProp<typeof ComboboxFn>
   ): JSX.Element
 }